As i am in almost the same boat as you ( i use Gtx 780 ).I had the same question whether to buy rx 480=gtx 1060 or 1070. As Archonar said there is no logic in updating your bios for those cards. As for performance the jump with 1070 would be quite noticeable.The money issue is present here also but a lot of guys said that i should wait a little longer and stretch to 1070 as it will be more future proof.